When deploying on IPv6 networks, set a hiera key that can be consumed
by puppet modules to configure MySQL or Galera appropriately.
Currently, this is required for configuring SST encryption in Galera
when Internal TLS is enabled [1].
[1] I1d6ee8febb596b3ab9dcde3a85a028ee99b2798c
Change-Id: Ia857350ac451fc1bda6659d85019962d3a9d5617
Partial-Bug: #1719885
(cherry picked from commit ff0a0dd987f4bcb997b271572ff0c901ed71d99b)